What causes acne on shoulders?

There are numbers of sebaceous glands on our shoulders, which release sebum. When the body releases an excess of sebum, it clogs the skin surface together with the dead skin cells and leads to dreaded pimples. Another common cause of acne on shoulders, Acne Mechanica, is triggered when heat is trapped in the body for a long period, and sweat is released. This blocks the follicles that then result in acne.